UA Investigators
Developing New Technology for Arthritic Joints
June 7, 2006
From: Janet Stark, (520)
626-7551
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Scientists at The University of Arizona College of
Medicine are investigating a potential new way to help patients
with arthritis who normally would have total-joint replacement.
Since the first joint-replacement
procedures more than 40 years ago, damaged knees, hips, shoulders and
other joints have been repaired with a variety of durable materials,
including ceramics, metals and plastics. Instead of replacing damaged
joints with these materials, John A. Szivek, PhD, and his team of
researchers are working on growing replacement tissues in his laboratory.
These tissues, which are grown from the patient's cells, are grown on a
plastic that will begin to dissolve after a year in the patient's body.
Dr. Szivek is a professor in the
UA Department of Orthopaedic
Surgery, director of the Orthopaedic Research Lab and a senior
scientist at the Arizona Arthritis
Center. With a $1.1 million grant awarded in 2002 by the
National Institutes of Health and an additional $368,000 grant from the
National Science Foundation, he and members of the UA Department of
Orthopaedic Surgery and the UA Biomedical Engineering Interdisciplinary
Program have been developing technology to grow new cartilage tissue to
replace damaged joints and to actively monitor loading on the joints when
patients exercise. |
When complete, this technology will have
the capacity to provide immediate feedback from a repaired joint while it is
being loaded during activity. Using a micro-miniature radio transmitter, data
will be transmitted directly from the joint to a hand-held computer or a
modified cell phone. Thus, an individual will be able to monitor effects on the
joint during various activities and avoid overstressing the joint.
One key component of the research is a
high-tech plastic carrier, or scaffold. Designed to support the growth of new
bone and cartilage, the scaffold also carries the load-sensing devices and the
radio transmitter that allows researchers to monitor the new tissue's response
to load.
The scaffold will be placed into the joint
to be repaired, Dr. Szivek explains. It is manufactured using a highly
sophisticated imaging device that scans the bone in tiny increments of just one
one-hundredth of a millimeter. These exact measurements of the bone are relayed
to a rapid prototyping machine that builds the scaffold, making it the exact
shape of the patient's bone. When placed, the scaffold, which is porous on the
inside, allows new bone tissue to grow into it.
The top of the scaffold is rounded to
support the growth of new cartilage in the lab, and the rounded shape will
conform to the surface of the patient's joint. After a year, the plastic device
will begin to dissolve, eventually leaving only the new tissue.
Dr. Szivek currently is concentrating on
two aspects of the project. One is the telemetry, or data-transmission process.
"We are the only people in the world working with the sensor technology," he
says. "We have developed the software that allows us to collect data and
transmit it to a Palm device, rather than a desktop or laptop computer. But we
need a faster, more powerful hand-held computer to collect the measurements. We
currently are able to collect measurements with an existing Palm device but will
be writing code for a hand-held computer running a Windows operating system that
has more functionality and memory."
The other major focus this year is growing
cartilage tissue from various types of cells. "The bone will grow into the
scaffold by itself once the scaffold is in the patient," Dr. Szivek says.
"However, we must grow the cartilage tissue in the lab before we implant it into
the patient." The process currently requires removing a small piece of cartilage
from the patient's affected joint, under anesthesia, and extracting cells in the
lab in order to grow new tissue on the scaffold. Unlike the cartilage in a
person's ear or nose, "hyaline articular cartilage" - the cartilage that
protects bone in joints - is complex and highly structured. It consists of three
layers of cells and tissue, with the cells distributed differently in each. The
cells do not divide or reproduce readily. If tissue forms, it forms very slowly.
This summer, Dr. Szivek is taking a new
approach to the problem. He is hoping to grow cartilage tissue from the stem
cells in fat, converting them to cartilage cells with the addition of proteins.
"I have hopes that these cells will be easier to work with than cartilage
cells," he says. "There are several advantages. One is the availability -
everyone has enough fat to do this, and harvesting fat from a patient is a
relatively simple procedure that is done under a local anesthetic. There are no
problems with tissue rejection, as the cells come from the same patient we plan
to implant the tissue into, and there are no embryonic stem cell issues."
While it is likely to be several years
before this technology is ready for clinical applications, it could replace
artificial-joint surgery for arthritis patients and others whose cartilage has
been damaged through trauma or sports, restoring the joint to more normal
function. It also will enable health-care professionals to monitor patients
during rehabilitation as well as providing an alert mechanism for patients if
they overload their tissue-engineered cartilage.
For
more information, please contact the Department of Orthopaedic Surgery, (520)
626-4024, or the
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